A pro cannabis festival that happens all over the US, not just Seattle, although the Seattle Hempfest is the biggest annual gathering that advocates the decriminalization of marijuana in the world.

Founded in 1991, it has grown to a two day fair, with over 100,000 in attendance. Hempfest has attracted many performers and speakers, such as The Kottonmouth Kings, and Dallas Cowboy's Mark Stepnoski.
In recent years, very few people have been arrested for the illegal use of marijuana the festival, and many openly smoke while in attendance.
Washington's Capital City, Olympia also has a small Hempfest the weekend after Seattle's every year.

Seattle's Hemp fest is held on the third week of August every year.
Boson, Portland, and half of the rest of Washington also have an annual Hempfest or rally.